Preliminary findings show a fatigue crack caused a Keystone Pipeline oil spill in North Dakota

BISMARCK, N.D. — A fatigue crack in the Keystone Pipeline led to an oil spill in North Dakota earlier this year that released thousands of barrels of oil onto farmland, according to the pipeline operator.

In a quarterly report released Thursday, South Bow said initial findings show, “the failure resulted from a fatigue crack that originated along the pipe’s manufactured long-seam weld.” A fatigue crack is a crack that grows larger with changes in pressure over time, Pipeline Safety Trust Executive Director Bill Caram said.

A mechanical and metallurgical analysis found the pipe and welds met industry standards, the company said.

Spill-related costs total around $55 million, which the company said it expects to recover through insurance early next year. Through September, South Bow had re